Prader-Willi syndrome (PWS) is associated with an assortment of physical, behavioural and cognitive abnormalities which create a broad range of care needs. Information about the syndrome is spread across a variety of disciplines. In this book the authors seek to identify and provide the latest findings about how best to manage the complex medical, nutritional, psychological, educational, social and therapeutic needs of people with PWS. Their approach is an integrated one, centred on the PWS phenotype. Both authors have been involved in the Cambridge PWS study, which is the largest and most rounded of the cohort studies of PWS anywhere in the world. The unique data it provides is the basis of this book.